Create and init QQuickTheme from QtQuickControls2Plugin

Instead of creating and setting the QQuickTheme instance from each
style plugin (e.g. QtQuickControls2MaterialStylePlugin), create the
QQuickTheme instance in QtQuickControls2Plugin when the style is
being resolved, and just pass the instance to be initialized by the
style plugin(s). This avoids the problem that QQuickTheme API was
virtual, and sub-classes created from plugins would have vtables
destroyed before the QQuickTheme was destroyed.

Task-number: QTBUG-67062
Task-number: QTBUG-68087
Change-Id: I19e9ced5296b708c2668c30163389cb3da6be7cf
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

3 files changed, 13 insertions, 19 deletions

diff --git a/src/imports/controls/universal/qquickuniversaltheme.cpp b/src/imports/controls/universal/qquickuniversaltheme.cpp
index 6485afbc..041dce9e 100644
--- a/src/imports/controls/universal/qquickuniversaltheme.cpp
+++ b/src/imports/controls/universal/qquickuniversaltheme.cpp
@@ -36,16 +36,12 @@
 
 #include "qquickuniversaltheme_p.h"
 
-#include <QtGui/qfont.h>
 #include <QtGui/qfontinfo.h>
+#include <QtQuickTemplates2/private/qquicktheme_p.h>
 
 QT_BEGIN_NAMESPACE
 
-QQuickUniversalTheme::QQuickUniversalTheme()
-{
-}
-
-void QQuickUniversalTheme::resolve()
+void QQuickUniversalTheme::initialize(QQuickTheme *theme)
 {
     QFont systemFont;
     QFont groupBoxTitleFont;
@@ -60,15 +56,15 @@ void QQuickUniversalTheme::resolve()
     }
 
     systemFont.setPixelSize(15);
-    setFont(System, systemFont);
+    theme->setFont(QQuickTheme::System, systemFont);
 
     groupBoxTitleFont.setPixelSize(15);
     groupBoxTitleFont.setWeight(QFont::DemiBold);
-    setFont(GroupBox, groupBoxTitleFont);
+    theme->setFont(QQuickTheme::GroupBox, groupBoxTitleFont);
 
     tabButtonFont.setPixelSize(24);
     tabButtonFont.setWeight(QFont::Light);
-    setFont(TabBar, tabButtonFont);
+    theme->setFont(QQuickTheme::TabBar, tabButtonFont);
 }
 
 QT_END_NAMESPACE
diff --git a/src/imports/controls/universal/qquickuniversaltheme_p.h b/src/imports/controls/universal/qquickuniversaltheme_p.h
index f0f18db5..f762d0e3 100644
--- a/src/imports/controls/universal/qquickuniversaltheme_p.h
+++ b/src/imports/controls/universal/qquickuniversaltheme_p.h
@@ -48,18 +48,16 @@
 // We mean it.
 //
 
-#include <QtGui/qfont.h>
-#include <QtQuickTemplates2/private/qquicktheme_p.h>
+#include <QtCore/qglobal.h>
 
 QT_BEGIN_NAMESPACE
 
-class QQuickUniversalTheme : public QQuickTheme
+class QQuickTheme;
+
+class QQuickUniversalTheme
 {
 public:
-    explicit QQuickUniversalTheme();
-
-protected:
-    void resolve() override;
+    static void initialize(QQuickTheme *theme);
 };
 
 QT_END_NAMESPACE
diff --git a/src/imports/controls/universal/qtquickcontrols2universalstyleplugin.cpp b/src/imports/controls/universal/qtquickcontrols2universalstyleplugin.cpp
index edc14327..1265f636 100644
--- a/src/imports/controls/universal/qtquickcontrols2universalstyleplugin.cpp
+++ b/src/imports/controls/universal/qtquickcontrols2universalstyleplugin.cpp
@@ -55,7 +55,7 @@ public:
     void registerTypes(const char *uri) override;
 
     QString name() const override;
-    QQuickTheme *createTheme() const override;
+    void initializeTheme(QQuickTheme *theme) override;
 };
 
 QtQuickControls2UniversalStylePlugin::QtQuickControls2UniversalStylePlugin(QObject *parent) : QQuickStylePlugin(parent)
@@ -85,9 +85,9 @@ QString QtQuickControls2UniversalStylePlugin::name() const
     return QStringLiteral("Universal");
 }
 
-QQuickTheme *QtQuickControls2UniversalStylePlugin::createTheme() const
+void QtQuickControls2UniversalStylePlugin::initializeTheme(QQuickTheme *theme)
 {
-    return new QQuickUniversalTheme;
+    QQuickUniversalTheme::initialize(theme);
 }
 
 QT_END_NAMESPACE